1. Field of the Invention
The present invention relates to a damper mechanism. More specifically, the present invention relates to a damper mechanism that transmits torque and damps torsional vibrations.
2. Background Information
Conventional damper mechanisms used in vehicle clutch disk assemblies typically have a hub, an input rotary member, and coil springs. The hub is coupled to a shaft extending from a transmission. The input rotary member is coupled to a flywheel. The coil springs elastically couple the hub and the input rotary member together in a rotational direction. The input rotary member has a clutch disk and pair of input plates fixed to the inner portion of the clutch disk. The hub has a boss that is splined to the shaft, and a flange that extends radially from the boss. The coil springs are housed in a plurality of spring housing holes formed in the hub and are supported in spring housing parts formed in the pair of input plates. When the pair of input plates rotate relative to the hub, the coil springs are compressed in the rotational direction between the plates and the hub. Typically, a damper mechanism absorbs and damps rotational twisting vibrations inputted to the clutch disk assembly. This kind of damper mechanism also has spring seats for supporting the end faces of the coil springs. Through the spring seats, the coil springs are supported by the spring housing holes of the hub and the spring housing parts of the pair of input plates.
Regarding spring seats, there are some that have a seat part that supports the end face of the coil spring and a pair of engaging parts that are formed on the rear surface of the seat part. The pair of engaging parts axially sandwich a circumferentially facing end of the spring housing hole. The pair of engaging parts allow the spring seat to engage with the circumferentially facing end of the spring housing hole such that the spring seat cannot rotate about the axis of the coil spring. Further, the outside portions of the pair of engaging parts engage with the spring housing parts such that the seat cannot rotate.
In the conventional damper mechanism just described, the spring seats are fixed so that they cannot rotate about the coil spring axes with respect to the spring housing holes and spring housing parts. Consequently, when the pair of input plates rotates relative to the hub and the coil springs are compressed in the damper rotational direction between the plates and the hub, one end of each coil spring is supported only by an end face of the spring housing hole and the other end of each coil spring is supported only by the spring housing parts. As a result, the coil springs are pressed against the edges of the spring housing parts due to centrifugal force and sliding, easily allowing the coil spring and spring housing parts to become worn and damaged.
In view of the above, there exists a need for a damper mechanism that overcomes the above-mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
An object of the present invention is to prevent wear and damage of the coil springs and spring housing parts in a damper mechanism.
In accordance with a first aspect of the present invention, a damper mechanism is arranged to transmit torque and damp torsional vibrations. The damper mechanism has a first rotary plate member, a pair of second rotary plate members, a coil spring, and a pair of spring seats. The first rotary plate member is formed with a spring housing hole. The pair of second rotary plate members is disposed so as to be fixed on opposite axially facing sides of the first rotary plate member. Each of the pair of second rotary plate members is formed with a spring housing part in a position that corresponds to the spring housing hole. The coil spring is arranged inside the spring housing hole and the spring housing parts, and can transmit torque between the first rotary plate member and the pair of second rotary plate members. Each of the pair of spring seats has a seat part that is disposed between an end of the coil spring and a circumferentially facing end of the spring housing hole/spring housing parts. Each spring seat supports the end face of the coil spring and a pair of engaging parts. The pair of engaging parts is aligned with the axial direction and extends from the opposite side of the seat part as the side that supports the coil spring. Further, the pair of engaging parts axially sandwiches the circumferentially facing end of the spring housing hole. Moreover, the engaging parts engage with the circumferentially facing end of each spring housing part such that they cannot rotate about the axis of the coil spring. The pair of engaging parts are of a pyramidal shape having its peak on the side opposite the side that supports the coil spring. Seat bearing parts corresponding to the pyramidal shape of the spring seats are formed in the circumferentially facing ends of the spring housing parts.
With this damper mechanism, when torque is delivered to the pair of second rotary plate members, torque is then transmitted to the first rotary plate member through the pair of spring seats and the coil spring. The torsional vibrations that occur during the torque transmission are absorbed and damped by compression of the coil spring in the rotational direction when the pair of second rotary plate members and the first rotary plate member rotate relative to each other. Here, the coil spring is compressed between the spring housing hole of the first rotary plate member and the spring housing parts of the second rotary plate members on the opposite side thereof.
The pair of engaging parts of the spring seat that contacts the spring housing hole sandwiches the circumferentially facing end of the spring housing hole of the first rotary plate member, and thus, cannot rotate about the axis of the coil spring relative to the spring housing hole. Since each of the pair of engaging parts of the spring seat that contacts the spring housing parts has a pyramidal shape, neither can rotate about the axis of the coil spring relative to the seat bearing parts on the circumferentially facing end of the spring housing parts of the second rotary plate members. Further, since the pair of engaging parts and the seat bearing parts have a pyramidal shape, the spring seats are prevented from rotating with respect to the spring housing parts, and therefore are restricted regarding movement in the radially outward direction caused by centrifugal force. As a result, it is difficult for the coil spring to slide on the edge sections of the spring housing parts. Thus, wear and damage of the coil spring and spring housing parts can be prevented. Additionally, the pair of engaging parts is formed to extend in the damper rotational direction. Consequently, the size of the spring seat can be reduced because the engaging parts do not occupy large amounts of space in the axial or radial directions of the damper.
A damping mechanism in accordance with a second aspect of the present invention is the mechanism of the first aspect wherein, each of the pair of engaging parts is provided with a first pyramid surface that is arranged on an axially inward side of the engaging part and faces axially toward a circumferentially facing end of the spring housing hole. Further, second and third pyramid surfaces are provided. The second and third pyramid surfaces are on an axially outward side of the engaging part and are aligned in a radial direction. The seat bearing parts of the damper mechanism of the second aspect have a pyramidal shape that matches the second and third pyramid surfaces of the engaging part.
With this damper mechanism, the spring seats can touch against and separate from the seat bearing part smoothly because the pair of engaging parts have a pyramidal shape having the second pyramid surface and third pyramid surface. Additionally, damage to the spring seats can be prevented because the contact area between the pair of engaging parts and the pair of seat bearing parts is large and the pressure on the contacting portions is small.
A damper mechanism in accordance with a third aspect of the present invention is the damper mechanism of the first or second aspect wherein, the coil spring is fixed such that it cannot rotate about the coil spring axis with respect to the spring seats. The spring seats support the end faces of the coil spring such that the coil spring cannot rotate about the its own axis. Further, the spring seat is supported such that it cannot rotate about the axis of the coil spring with respect to the spring housing parts.
As a result, when using a coil spring having end windings, the spring can be held in an orientation where the side of the coil spring closer to the center of the damper mechanism has one more winding than the side of the coil spring closer to the outside of the damper mechanism. Thus, the difference in per-winding deflection between the two sides of the coil spring and the difference in stress between the two sides of each winding that occur when the coil spring is compressed can both be reduced.
These and other objects, features, aspects, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.